Quakes spurred on faults unmoved for 300 million years

Earthquakes that have swarmed North Texas in recent years occurred on faults awakened by human activity after they had lain dormant since dinosaurs roamed the area, according to a new university study.

There have been frequent earthquakes in recent years in the Fort Worth Basin, from the rural town of Venus to the heavily developed Dallas suburb of Irving, along faults that had been silent for more than 300 million years, according to the study by Southern Methodist University researchers published online last week in the journal Science Advances.

The study's conclusion supports recent assertions that the earthquakes were induced by human activity, not naturally. That conclusion is independent of previous study results that correlated earth tremors to the timing of wastewater injection associated with the hydraulic fracturing process — or fracking — of oil and gas drilling. However, it corroborates those previous findings, the researchers said.

"The study's findings suggest that the recent Fort Worth Basin earthquakes, which involve swarms of activity on several faults in the region, have been induced by human activity," said Michael Blanpied, associate coordinator of the Earthquake hazard program of the U.S. Geological Survey and a co-author of the SMU report.

Furthermore, the findings suggest that the North Texas earthquakes are not just happening sooner than they would otherwise along longdormant faults, they suggest that waste fluid injection has actually reawakened those faults, Blanpied said.

Texas, Oklahoma and other states have had earthquakes in recent years that scientists have linked to wastewater injection wells.

In a statement Friday, a spokeswoman for the Texas Railroad Commission, the agency that regulates oil and gas drilling, said the commission "has long recognized the possibility of induced seismicity related to fluid injection."